Field of the Disclosure
This disclosure relates to a liquid crystal display (LCD) device, and more particularly to an LCD device adapted to stably apply a start pulse signal to an internal driving circuit regardless of the generation of static electricity on a start pulse signal input line.
Description of the Related Art
In general, the LCD device includes an LCD panel and driving circuits which are configured to drive the LCD panel. The LCD panel is configured to include a thin film transistor array substrate and a color filter substrate opposite to each other, and a liquid crystal layer interposed between the two substrates. The thin film transistor array substrate and the color filter substrate are combined to maintain a fixed cell gap. The liquid crystal layer is formed in the fixed cell gap.
The driving circuits include at least two gate driver integrated-circuit chips, at least two data driver integrated-circuit chips, a timing controller, and a power supply unit. The gate driver integrated-circuits sequentially apply a scan signal to gate lines on the LCD panel. The data driver integrated-circuit chips apply image information to pixels through data lines on the LCD panel, in synchronization with the sequential supply of scan signal from the gate driver integrated-circuit chips. The timing controller controls the gate and data driver integrated-circuit chips. The power supply unit generates a variety of driving voltages necessary to drive the LCD device.
Such driver integrated-circuit chips are generally connected to the LCD panel in a TAP (tape automated bonding) system or a COG (chip-on-glass) system. The TAP system mounts at least one driver integrated-circuit on a flexible thin-film made from a high polymer material and connects the flexible thin-film with the LCD panel. In other words, the TAP system combines at least one driver integrated-circuits chip and a flexible thin-film in a package (i.e., a tape carrier package (TCP)) and connects the package with the LCD panel. As such, the TAP system is often referred to as a TCP (tape carrier package) system. The COG system mounts the driver integrated-circuit chips on the LCD panel, thereby directly connecting the driver integrated-circuit chips with the LCD panel.
More specifically, the TAB system attaches at least one TCP on the exposed edges of the thin film transistor array substrate. This results from the fact that the edges of the thin film transistor array substrate are exposed at the combination with the color filter substrate because its area is larger than that of the color filter substrate.
Also, the COP system can enable control signals and driving voltages from the timing controller and the power supply unit to be applied to the gate and data driver integrated-circuit chips through a plurality of signal lines on the LCD panel. To rectify this, the COG system can transmit the control signal and the driving voltages using the plurality of signal lines formed in a LOG (line-on-glass) type.
Similarly, the TAB system also can employ the LOG type signal lines, in order to eliminate at least one PCB (printed circuit board) and make the LCD device slimmer. The gate driver integrated-circuit chips requiring relatively small signal lines use the LOG type signal lines formed on the LCD panel, thereby eliminating a gate PCB. In this case, the gate driver integrated-circuit chips receive the control signals and the driving voltages from the timing controller and the power supply unit, which are mounted on a data PCB, through the LOG type signal lines formed on the thin film transistor array substrate.
Among the control signals applied from the timing controller to the LOG type signal lines, a start pulse signal for controlling the driving timing of the gate driver integrated-circuit chips has a very short on-time (or a very short enabling time). Such a start pulse signal of this very short enabling time induces a high impulse voltage to be applied to the LOG type signal lines, thereby generating static electricity on the LOG type signal lines.
Static electricity forces the start pulse signal to not be often input to the gate driver integrated-circuit chips with the desired timing. Also, static electricity frequently affects other signals on the LOG type signal lines adjacent to the start pulse signal line of the LOG type. Accordingly, a malfunction of the gate driver integrated-circuit chip is caused.